Study on capillaries covalently bound with phospholipid vesicles for open‐tubular CEC and application to on‐line open‐tubular CEC‐MS

Abstract

Phospholipid vesicles were covalently attached to iminoaldehyde-coated fused silica capillaries and applied to the separation of model steroids by open-tubular CEC (OT-CEC). The effects of reducing the formed Schiff's base with sodium borohydride and of the liposome composition on the stability of the coating were investigated. In addition, the studies were focused on the optimization of running conditions (pH values and composition of BGE solution) when CEC, using capillaries covalently bound with liposome dispersions, was coupled to MS. The effect of cholesterol in the liposome dispersion on the binding of model analytes was studied, using liposome dispersions comprising 80/20 mol% zwitterionic 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine (POPC) and the negatively charged phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS) and 40/40/20 mol% POPC/POPS/cholesterol. Cholesterol in liposomes (greatly) enhanced the stability of the capillaries by making the coatings more rigid, resulting in lower retention factors for all the studied model steroids. Although most of the studies were carried out by open tubular CEC-UV Vis, the applicability of the capillaries to on-line CEC-MS was demonstrated as well. On-line CEC-MS studies on model steroids proved the suitability of coated capillaries for analyte-lipid membrane interaction studies, and especially for such analytes that are difficult to detect by conventional on-line UV Vis.

Open tubular‐capillary electrochromatography: Developments and applications from 2013 to 2015

“… and Xu et al. achieved separations of small molecules using MOFs with the aromatic framework of 1,3,5‐benzenetricarboxylic acid, while Tiala and coworkers have separated steroids using phospholipid vesicles . Other interesting work, carried out by Zhang and coworkers, describe the use of a reversed‐phase‐like separation of benzene derivatives using hydroxyapatite with a polydopamine coating .…”

“…Li and coworkers have separated aromatic acids by OT-CEC according to the degree of their hydrophobicity using an MOF composite coating [14], while Yu and coworkers have separated neutral analytes using a ZIF-90 framework containing an organic ligand imidazolium ring [22]. The groups of Bao et al [63] and Xu et al [64] achieved separations of small molecules using MOFs with the aromatic framework of 1,3,5-benzenetricarboxylic acid, while Tiala and coworkers have separated steroids using phospholipid vesicles [20]. Other interesting work, carried out by Zhang and coworkers, describe the use of a reversed-phase-like separation of benzene derivatives using hydroxyapatite with a polydopamine coating [34].…”

“…Table A‐2 summarizes examples of the use of preformed SP materials, i.e. phospholipid vesicles , block copolymers , zeolitic imidazole frameworks , derivatized chitosan , and bacterial antibiotic‐based materials, all of which can be immobilized onto the inner wall of fused silica capillaries. Fabrication of phospholipid vesicle‐based SP materials can be achieved by aminopropylsilylation of the surface silanol groups, followed by treatment with glutaraldehyde, forming iminoaldehyde functionalities.…”

Influences of the concentration and the molar ratio of mixed surfactants on the performance of vesicle pseudostationary phase

“…After that, the researchers had obtained the vesicles that were formed spontaneously from many mixed systems, such as amphoteric and anionic surfactants, nonionic surfactant and cosurfactant, and anionic and cationic surfactants. Because of the special properties and structures, the vesicles play a great role in the fields of capillary electrokinetic chromatography , biological simulation , drug encapsulation and targeted release , microreactor , capillary LC , and open‐tubular CEC .…”

Preparation and evaluation of 3 m open tubular capillary columns with a zwitterionic polymeric porous layer for liquid chromatography

“…However, zwitterionic‐based OT columns have rarely been reported. Although poly‐ε‐sodium‐undecanoyl lysinate , phenylalanine , 1‐palmitoyl‐2‐oleylsn‐glycerol‐3‐phosphocholine, and 1‐palmitoyl‐2‐oleoylsn‐glycerol‐3‐phospho‐ l ‐serine have been used to prepare OT column, the separations of these columns depend on electrophoresis behavior of samples instead of superhydrophilicity of zwitterionic stationary phase. Herein, we have prepared a zwitterionic polymer coating inside a 25 μm id fused‐silica capillary by atom transfer radical polymerization of [2‐(methacryloyloxy) ethyl] dimethyl‐(3‐sulfopropyl) ammonium hydroxide (MSA) and N , N ’‐methylenebis(acrylamide) (MBA).…”